zig-opengl/build.zig

const std = @import("std");

// Although this function looks imperative, note that its job is to
// declaratively construct a build graph that will be executed by an external
// runner.
pub fn build(b: *std.Build) void {
    // Standard target options allows the person running `zig build` to choose
    // what target to build for. Here we do not override the defaults, which
    // means any target is allowed, and the default is native. Other options
    // for restricting supported target set are available.
    const target = b.standardTargetOptions(.{});

    // Standard optimization options allow the person running `zig build` to select
    // between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
    // set a preferred release mode, allowing the user to decide how to optimize.
    const optimize = b.standardOptimizeOption(.{});

    const exe = b.addExecutable(.{
        .name = "zig-opengl",
        .root_source_file = b.path("src/main.zig"),
        .target = target,
        .optimize = optimize,
    });

    const glfw_dev_path = b.graph.env_map.get("GLFW_DEV_PATH");
    const libgl_path = b.graph.env_map.get("LIBGL_DEV_PATH");

    if (glfw_dev_path == null) {
        std.debug.panic("GLFW_DEV_PATH environment variable was not set. Has the nix flake been updated? This should point at the glfw folder", .{});
    }

    if (libgl_path == null) {
        std.debug.panic("LIBGL_DEV_PATH environt was not set. Has the nix flake been updated? This should point to the libGL folder", .{});
    }

    exe.addIncludePath(.{ .cwd_relative = b.fmt("{s}/include", .{ libgl_path.? }) });
    exe.addIncludePath(.{ .cwd_relative = b.fmt("{s}/include", .{ glfw_dev_path.? }) });
    exe.addIncludePath(.{ .cwd_relative = b.fmt("./lib", .{}) });

    exe.addCSourceFile(.{ 
        .file = b.path("lib/glad/gl.c"), 
        .flags = &.{"-std=c99"}
    });

    exe.linkSystemLibrary("glfw");

    // exe.addIncludePath(.{ .cwd_relative = b.fmt("$GLIB_DEV_PATH/include/GL", .{}) });
    exe.linkLibC();


    // This declares intent for the executable to be installed into the
    // standard location when the user invokes the "install" step (the default
    // step when running `zig build`).
    b.installArtifact(exe);

    // This *creates* a Run step in the build graph, to be executed when another
    // step is evaluated that depends on it. The next line below will establish
    // such a dependency.
    const run_cmd = b.addRunArtifact(exe);

    // By making the run step depend on the install step, it will be run from the
    // installation directory rather than directly from within the cache directory.
    // This is not necessary, however, if the application depends on other installed
    // files, this ensures they will be present and in the expected location.
    run_cmd.step.dependOn(b.getInstallStep());

    // This allows the user to pass arguments to the application in the build
    // command itself, like this: `zig build run -- arg1 arg2 etc`
    if (b.args) |args| {
        run_cmd.addArgs(args);
    }

    // This creates a build step. It will be visible in the `zig build --help` menu,
    // and can be selected like this: `zig build run`
    // This will evaluate the `run` step rather than the default, which is "install".
    const run_step = b.step("run", "Run the app");
    run_step.dependOn(&run_cmd.step);

    // Creates a step for unit testing. This only builds the test executable
    // but does not run it.
    const lib_unit_tests = b.addTest(.{
        .root_source_file = b.path("src/root.zig"),
        .target = target,
        .optimize = optimize,
    });

    const run_lib_unit_tests = b.addRunArtifact(lib_unit_tests);

    const exe_unit_tests = b.addTest(.{
        .root_source_file = b.path("src/main.zig"),
        .target = target,
        .optimize = optimize,
    });

    const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);

    // Similar to creating the run step earlier, this exposes a `test` step to
    // the `zig build --help` menu, providing a way for the user to request
    // running the unit tests.
    const test_step = b.step("test", "Run unit tests");
    test_step.dependOn(&run_lib_unit_tests.step);
    test_step.dependOn(&run_exe_unit_tests.step);
}